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A. General Structure and Function: Three major pairs of glands, the parotid, submandibular, and sublingual, surround the oral cavity. The lobules of each gland contain numerous adenomeres that empty their secretions (saliva) through a series of intercalated, striated, and interlobular ducts into the oral cavity. The saliva moistens the food, lubricates the digestive tract, and begins the enzymatic digestion of carbohydrates. The glands also excrete certain salts; they protect against bacterial invasion through the mouth by releasing lysozyme and IgA into the saliva.

B. Cell Types:

1. Serous and mucous cells are the predominant secretory cells of salivary adenomeres of digestive system. The key to identifying the 3 types of salivary glands in tissue sections lies in knowing the differences in the staining properties of the cells, their organization, and the proportion of each type found in each gland. a. Serous cells. These relatively small basophilic cells produce a protein-rich, watery secretion and usually form acinar (spheric) adenomeres. b. Mucous cells. Larger and more acidophilic than the serous cells, these may have a foamy appearance. They produce a thick glycosaminoglycan-rich secretion (mucus) and usually form tubular adenomeres.

C. Parotid Glands: These branched acinar glands contain almost exclusively serous secretory cells. The granules in these cells are PAS-positive (owing to their polysaccharide content) and are rich in protein. Parotid secretions, about 25% of the total salivary volume.

D. Submandibular (Submaxillary) Glands: These branched tubuloacinar glands, which produce about 70% of the salivary volume, contain both serous and mucous adenomeres (mostly serous). The serous acini are composed of small basophilic cells with PAS-positive cytoplasm and basal membrane infoldings.

E. Sublingual Glands: These are also branched tubuloalveolar glands containing both mucous and serous cells (mostly mucous). While only mucous adenomeres are present, many are capped by serous demilunes. These glands produce about 5% of the salivary volume.